It is conventional to use filters and separators for removing foreign objects, and condensing and removing water and other condensable liquids, from pressurized air lines and the like. Typically, such filters include an air inlet, an air outlet and a filtering element mounted between these elements in the flow path. Such filters also include a reservoir or filter bowl through which the air flow is at least partially passed causing the moisture and other condensables in the air to be coalesced and condensed on the inside surface of the reservoir or bowl. The force of gravity causes such condensed materials to accumulate at the bottom of the reservoir together with any other foreign objects. Periodically, this accumulated material must be discharged when the reservoir or filter bowl has become full of material.
Various types of drain systems with automatic valves have been devised to discharge such accumulated material. Examples of such devices are shown in U.S. Pat. No. 3,993,090 issued to Paul M. Hankinson, and in U.S. Pat. Nos. 4,444,217, 4,562,855, and 4,574,829 all of which are issued to Ernie W. Cummings and Nick Valk. All the above patents disclose the use of magnetic coupling members within a reservoir which translate the movement of a float within the reservoir to open and close a pilot valve which in turn causes the opening and closing of a drain valve. When the reservoir fills with water and the float rises the magnetic coupling members interact to open the pilot valve and thereby open the drain valve. When the float returns to the bottom of the reservoir the magnetic coupling members interact to cause the pilot valve to close and thereby close the drain valve.
A problem can occur in the devices described in the above patents when the magnetic coupling members and related moving parts become coated with corrosion or other or deposits of contaminates which may be present in the water. Such accumulations can cause a failure of the float to rise properly or the pilot valve may stick in either the open or closed position. The present invention eliminates the need for magnetic coupling devices which may be prone to sticking when accumulations of corrosion and contaminates are present on the surface of the magnetic coupling members and other related working parts of the drain valve system.